The first time the scene of the laser moving in the air was recorded

By using a speed camera of approximately 20 billion frames per second, scientists have returned to the video for the first time to show a laser beam moving in the air for 6 nanoseconds.

Previously, this was a scene that only appeared in sci-fi films, built with cinematic techniques but never been recorded in reality. The successful layout of this experiment, scientists can not only overcome a challenge in science, but also create a premise to open many other important discoveries in the future such as hidden object cameras or phenomena take place at a very fast moment.

The sight of using a laser gun to shoot long traces of air in the air just now appeared in sci-fi movies, in fact we could hardly see it. To capture the laser's movement , or any other light source, the photons from that must go directly into the human eye. But often the laser photons in the beam will be focused on the same point, so that when this beam hits an object, we can see a tiny dot on the object.

Photograph of the laser beam moving in the air

Although there is also a small fraction of laser photons scattered by molecules in the air, often this amount of light is too small to be seen with the naked eye. In fact, we can see this when firing a laser through a smoke so that they are more scattered. However, scientists always wanted to get back to the laser beam scene just like in a movie. Genevieve Gariepy, Ph.D. at Heriot-Watt University, said: "The challenge here is to get back to the path of light like in a movie. We want to see the light without affecting it, simply watch it move. "

Arrangement of the laser motion scene of the research team

To do this, Gariepy and her colleagues built a camera that is sensitive enough to capture the motion of several photons. This camera is made up of a 32x32 sensor grid that can record the travel time of a photon with amazing precision, equivalent to a rate of about 20 billion frames per second and 1024 pixel resolution. Then, the group shoots a green laser beam into a mirror to reflect it. 2 million laser pulses were fired for about 10 minutes and the process was minimized to noise, eventually the group created enough scattering laser photons into the air that the camera could record the path of it.

Initially, the group intended to make the fictional film scene a reality, but Gariepy said that successful experiments opened up more practical applications in the future. Information about photon movement can provide data on both space and time channels. Time information can be used to study dynamic processes that occur at extremely fast times, while spatial data can be used to capture hidden objects by calculating the process. light hits the object and reflects back to the camera.